SINGAPORE, June 26 (Reuters) - China United Network Communications Ltd said on Monday its controlling shareholder planned to bring strategic investors into the unit via a private share placement, but said details had not been finalised.

Reuters reported last week that Chinese tech giants Alibaba Group Holdings and Tencent Holdings would be among new investors pouring about $10 billion into China Unicom, the country's second largest telecom carrier.

China United Network Communications Ltd said in a statement issued on the Shanghai stock exchange that its controlling shareholder, state-owned China United Network Communications Group Co Ltd (China Unicom), planned the placement.

"However, specific plans of the private placement, including targeted investors, issue size, price and use of proceeds, are at the preliminary stages and nothing has been decided yet," the Shanghai-listed unit said.

Four sources had told Reuters that Alibaba and Tencent would invest in the Shanghai-listed unit, part of a capital-raising effort that Thomson Reuters data showed would be the biggest in Asia since the initial public offering of insurer AIA Group in 2010.

The move by China Unicom is part of a bid by China's government to rejuvenate state behemoths with private cash.